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Calcium buffering of resting, voltage-dependent Ca2+ influx by sarcoplasmic reticulum in femoral arteries from spontaneously hypertensive rats at prehypertensive stage.
- Source :
-
Hypertension research : official journal of the Japanese Society of Hypertension [Hypertens Res] 2001 May; Vol. 24 (3), pp. 271-82. - Publication Year :
- 2001
-
Abstract
- We examined the Ca2+-buffering function of the sarcoplasmic reticulum (SR) in the resting state of arteries from spontaneously hypertensive rats (SHR) at a prehypertensive stage. Differences in the effects of cyclopiazonic acid (CPA) and thapsigargin, agents that inhibit SR Ca2+-ATPase, and of ryanodine, which depletes SR Ca2+, on tension and cellular Ca2+ level were assessed in endothelium-denuded strips of femoral arteries from 4-week-old SHR and normotensive Wistar-Kyoto rats (WKY). Addition of CPA, thapsigargin or ryanodine to the resting state of the strips caused an elevation of cytosolic Ca2+ level and a contraction in both WKY and SHR. These responses were larger in SHR than in WKY. The contractions were inhibited strongly by 100 nM nifedipine or 3 microM verapamil and were abolished by Ca2+-free solution. Nifedipine, verapamil or Ca2+-free solution itself caused a relaxation from the resting state of SHR strips, but not from that of WKY strips. The resting Ca2+ influx in arteries measured by a 5-min incubation with 45Ca was significantly larger in SHR than in WKY. This influx was decreased by 10 microM CPA or 10 microM ryanodine in both WKY and SHR. These results suggest that in the resting state of the femoral artery from 4-week-old SHR, the greater part of the increased Ca2+ influx via L-type Ca2+ channels is buffered by Ca2+ uptake into the SR, while some Ca2+ reaches the myofilaments, resulting in the maintenance of resting tone.
- Subjects :
- 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester pharmacology
Animals
Calcium Channel Agonists pharmacology
Calcium Channel Blockers pharmacology
Calcium Radioisotopes pharmacokinetics
Calcium-Transporting ATPases antagonists & inhibitors
Calcium-Transporting ATPases metabolism
Enzyme Inhibitors pharmacology
Femoral Artery drug effects
Indoles pharmacology
Male
Muscle Contraction drug effects
Nifedipine pharmacology
Potassium pharmacology
Rats
Rats, Inbred SHR
Rats, Inbred WKY
Ryanodine pharmacology
Sarcoplasmic Reticulum drug effects
Sarcoplasmic Reticulum Calcium-Transporting ATPases
Thapsigargin pharmacology
Verapamil pharmacology
Calcium metabolism
Calcium Channels, L-Type metabolism
Femoral Artery metabolism
Hypertension metabolism
Sarcoplasmic Reticulum metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 0916-9636
- Volume :
- 24
- Issue :
- 3
- Database :
- MEDLINE
- Journal :
- Hypertension research : official journal of the Japanese Society of Hypertension
- Publication Type :
- Academic Journal
- Accession number :
- 11409650
- Full Text :
- https://doi.org/10.1291/hypres.24.271